In modern medicine, medical images captured by X-ray irradiation, CT and MRI play important roles for diagnosing patients or making decision in treating the patients. Accordingly, obtaining high-quality images with less noise is necessary in medical imaging examinations. A medical image is produced by physical energy in which image signals are generated through the reaction of the physical energy with the body and detected by a detector. So, in the medical image obtaining procedure, noise is unavoidably included in the image due to slight variations in an energy generating source and energy distribution in space as well as the occurrence of thermodynamic noise within the detector. Especially in X-rap and CT examinations that use ionizing radiation, in order to reduce potential harm due to radiation exposure, it is necessary to reduce a radiation dose exposure when capturing the medical image. However, a reduction of the radiation dose causes an increased noise level in the medical image.
An important step in imaging examination chain is the application of appropriate post processing technique which reduces the image noise generated at the time of image capture, in order to increase the value of clinical utilization of the medical image.
However, a general method of reducing noise in the field of image processing is primarily focused to enhance visual comfort. For this reason, mechanisms that prevent the degradation of structural properties within the image caused by the noise reduction procedure are not sufficiently provided. The degradation of an important anatomical structure or lesion shape caused by the noise reduction procedure may lead to an error in imaging diagnosis, which may in turn bring about a serious consequence in patient care. Accordingly, the noise reduction method of the medical image needs to have specially tuned mechanisms unlike those techniques used in a general application field.